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[93.146.37.148]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-ac239485bf3sm755327266b.63.2025.03.10.03.50.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 10 Mar 2025 03:50:29 -0700 (PDT) Date: Mon, 10 Mar 2025 11:50:28 +0100 From: Lorenzo Bianconi To: arthur@arthurfabre.com Cc: netdev@vger.kernel.org, bpf@vger.kernel.org, jakub@cloudflare.com, hawk@kernel.org, yan@cloudflare.com, jbrandeburg@cloudflare.com, thoiland@redhat.com, lbiancon@redhat.com, Arthur Fabre Subject: Re: [PATCH RFC bpf-next 05/20] trait: Replace memcpy calls with inline copies Message-ID: References: <20250305-afabre-traits-010-rfc2-v1-0-d0ecfb869797@cloudflare.com> <20250305-afabre-traits-010-rfc2-v1-5-d0ecfb869797@cloudflare.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="8LdxVSwL0xr9PrwX" Content-Disposition: inline In-Reply-To: <20250305-afabre-traits-010-rfc2-v1-5-d0ecfb869797@cloudflare.com> --8LdxVSwL0xr9PrwX Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable > From: Arthur Fabre >=20 > When copying trait values to or from the caller, the size isn't a > constant so memcpy() ends up being a function call. >=20 > Replace it with an inline implementation that only handles the sizes we > support. >=20 > We store values "packed", so they won't necessarily be 4 or 8 byte > aligned. >=20 > Setting and getting traits is roughly ~40% faster. Nice! I guess in a formal series this patch can be squashed with patch 1/20 (adding some comments). Regards, Lorenzo >=20 > Signed-off-by: Arthur Fabre > --- > include/net/trait.h | 25 +++++++++++++++++++------ > 1 file changed, 19 insertions(+), 6 deletions(-) >=20 > diff --git a/include/net/trait.h b/include/net/trait.h > index 536b8a17dbbc091b4d1a4d7b4b21c1e36adea86a..d4581a877bd57a32e2ad03214= 7c906764d6d37f8 100644 > --- a/include/net/trait.h > +++ b/include/net/trait.h > @@ -7,6 +7,7 @@ > #include > #include > #include > +#include > =20 > /* Traits are a very limited KV store, with: > * - 64 keys (0-63). > @@ -145,23 +146,23 @@ int trait_set(void *traits, void *hard_end, u64 key= , const void *val, u64 len, u > memmove(traits + off + len, traits + off, traits_size(traits) - off); > } > =20 > - /* Set our value. */ > - memcpy(traits + off, val, len); > - > - /* Store our length in header. */ > u64 encode_len =3D 0; > - > switch (len) { > case 2: > + /* Values are least two bytes, so they'll be two byte aligned */ > + *(u16 *)(traits + off) =3D *(u16 *)val; > encode_len =3D 1; > break; > case 4: > + put_unaligned(*(u32 *)val, (u32 *)(traits + off)); > encode_len =3D 2; > break; > case 8: > + put_unaligned(*(u64 *)val, (u64 *)(traits + off)); > encode_len =3D 3; > break; > } > + > h->high |=3D (encode_len >> 1) << key; > h->low |=3D (encode_len & 1) << key; > return 0; > @@ -201,7 +202,19 @@ int trait_get(void *traits, u64 key, void *val, u64 = val_len) > if (real_len > val_len) > return -ENOSPC; > =20 > - memcpy(val, traits + off, real_len); > + switch (real_len) { > + case 2: > + /* Values are least two bytes, so they'll be two byte aligned */ > + *(u16 *)val =3D *(u16 *)(traits + off); > + break; > + case 4: > + *(u32 *)val =3D get_unaligned((u32 *)(traits + off)); > + break; > + case 8: > + *(u64 *)val =3D get_unaligned((u64 *)(traits + off)); > + break; > + } > + > return real_len; > } > =20 >=20 > --=20 > 2.43.0 >=20 >=20 --8LdxVSwL0xr9PrwX Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYKAB0WIQTquNwa3Txd3rGGn7Y6cBh0uS2trAUCZ87D9AAKCRA6cBh0uS2t rKiHAP4ig6AB4OYPje30z4tiswFLGKvRQKjJfOWR/9sexp8ODgEA3c2LJVAALxka vA6BEzSCv3QLZX1Pd1LJJjsBU766WAQ= =iMCa -----END PGP SIGNATURE----- --8LdxVSwL0xr9PrwX--